Adjustable-while-running oscillator



March 14, 1961 A. J. YORGIADIS 2,974,536

ADJUSTABLE-WHILE-RUNNING oscILLAToR Filed March 5, 1959 5 Sheets-Sheet 2 INVENTOR A.J. YoRGlAols ATTORNEY FIG 3 March 14, 1961 A. J. YoRGlADls ADJUsTABLE-wmLE-RUNNING oscILLAToR 5 Sheets-Sheet 3 Filed March 5, 1959 INVENTOR AfJ. YORGIADS ATTORNEY March 14, 1961 A. J. YoRGxADls 2,974,536

.ADJ USTABLE-WHILE-RUNNING OSCILLATOR Filed March 5. 1959 5 Sheets-Sheet 4 NVENTOR N A.J. YORGIADIS March 14, 1961 A. J. YoRGlADls 2,974,535

ADJUsTABLE-wmLE-RUNNING oscILLAToR Filed March 5. 1959 5 sheets-sheet 5 xNvENToR AJ. -YORGIADIS United States ADJ USTABLE-WHILE-RUNNING OSCILLATOR Filed Mar. 5, 1959, Ser. No. 797,453

Claims. (Cl. 74--61) This invention relates to oscillator apparatus and more particularly to the type that is adjustable While running.

As is well known as oscillator includes a revolving eccentric weight or weights for producing a vibratory force on a test structure to which the oscillator is attached or in a fatigue testing machine of which the oscillator is an integral component. Oscillators may be of the -xed type which must be stopped to adjust the eccentricity 0f the weights to change the vibratory force, or they may be of the type in which the eccentricity may be adjusted while the oscillator is running. The so-called tixed type of oscillator is suliiciently rugged that it can be built in large sizes and capacities but the inability to adjust such f an oscillator while running causes a serious limitation in its use such, for example, as programming operations or the like.

Previous attempts to provide adjustable-whilerunning oscillators have resulted in adjusting mechanisms that inherently do not possess sufficient ruggedness to permit such oscillators to be built in large sizes and capacities. Certain of these prior adjustable-while-running oscillators have employed spiral keyways and keys, cams, or other arrangements that are structurally, functionally or economically unsound in large sizes and capacities. Other attempts to overcome these problems have involved the use of relatively angularly adjustable opposed weights, but the angular adjustment of such weights do not have a linear relation between equal angular degrees of movement of the adjusting mechanism and the force produced for corresponding angular positions of the weights. There has also been the problem of adequately locking the weights in their various adjusted positions without causing the locking or holding forces to be transmitted substantially the entire adjusting mechanism itself.

It is an object of my invention to provide an improved adjustable-while-running oscillator apparatus that has a high degree of ruggedness so that it is possible to build the oscillator in large sizes and capacities while at the same time obtaining maximum flexibility and ease of control of the eccentricity of the revolving weights.

Another object is to provide an improved adjustable oscillator apparatus that has a linear relationship in which a given movement of the adjusting mechanism will produce the same increment of eccentricity or unbalance at all times and positions of the adjusting mechanism.

An additional object is to provide an adjustable oscillator with an improved inherent self-locking feature that eliminates the need for auxiliary locking mechanisms and that will not load the adjusting or driving mechanisms outside of the oscillator.

A further object is to provide improved means for reducing the capacity of an adjustable force producing eccentric weight without sacrificing the full capacity of the oscillator.

A still further object is to provide an improved adjustable-while-running oscillator apparatus that is relatively economical in construction, operation, and maintenance with due consideration given to the large capacities latent G i 2,974,536 Patented Mar. 14, 1961 ICC and sizes in which my oscillator apparatus can be built and to accomplish this while retaining all of the desirable qualities of exibility and ease of operation, linearity, and freedom from other difficulties heretofore experienced with oscillators.

Other objects and advantages will be more apparent to those skilled in the art from the following description of the accompanying drawings in which:

Fig. l is a diagrammatic longitudinal section through a fatigue testing machine in which my improved oscillator is a component, the oscillator being shown in an angular position so that the eccentric weight is on the right side of its axis of rotation;

Fig. 2 is a diagrammatic outline of my improved driving and adjusting mechanisms for the oscillator;

Fig. 3 is a fragmentary perspective of the eccentric weight and the mechanism for adjusting its eccentricity with certain parts broken away to show details of construction, the oscillator in this View having been rotated to a position to show the eccentric weight on the left side of its axis of rotation;

Fig. 4 is a transverse section taken substantially on the line 4 4 of Figs. l, 3 and 5, and shows the oscillator taken through its axis of rotation;

Fig. 5 is a longitudinal section taken substantially on the line -5--5 of Fig. 4 and shows the oscillator in the plane at right angle to its rotation; and

Figs. 6 and 7 are diagrammatic illustrations of modied arrangements of differential controls for adjusting the eccentricity of the oscillator weights.

The overall oscillator apparatus comprising my invention includes a mechanical oscillator, per se, a main drive for the oscillator, a drive for the adjustment of the oscillator setting, and a means for measurement of the oscillator position. One example of the internal construction of the mechanical oscillator is shown in Figs. 3, 4 and 5. A movable mass which produces the unbalance of the oscillator consists of two weights or blocks 1 and 2, preferably rectangular, connected solidly to each other through two parallel adjusting screws 3 and 4 of right and left hand threads respectively and of the same pitch. The enlarged ends of the adjusting screws are nonrotatably held relative to the weights by pins 5 while the other ends are held by studs 7. The screws are threaded in and are axially moved oy two internally threaded worm gears 8 and 9 superimposed over each other in generally tangential relation and rotated about parallel axes by a common worm 10 interposed between the Worm gears thereby producing opposite rotation thereof to move the weights 1 and 2 to a desired degree of eccentricity. The worm gears 8 and 9 are supported in a rotating oscillator housing or frame 11 through pairs of bearings 12, 12 and 13, 13 while the worm 10 is journalled in the housing by bearings 14.

The housing is rotatably supported by bearings 15 and 16 disposed in brackets 17 and 18. Because the oscillator is shown herein as a component of a fatigue testing machine 19, Fig. 1, the brackets 17 and 18 are shown as connected by studs 20 to one end of the vibratory specimen loading lever 21 which is pivoted about an axis 22 of crossed supporting ex plates 23 to transmit vibratory loads to specimen platforms 24 and 25. This type of machine is well known and is generally disclosed in application 4of Ali U. Kutsay, Serial No. 501,469, tiled April 15, 1955, now Patent No. 2,882,720. The machine, per se, does not constitute a part of the present invention except as to the relation of the adjusting mechanism to the pivotal movement of the testing machine lever 21. If the oscillator is to be attached to a test structure instead of forming a component of the testing machine the brackets 17 and 18 could serve as the attaching means. The

3 housing is rotatably driven in a manner to be described and thereby rotate the weights about the axis 26, which is the common axis of the worm and housing, to produce a desired force from zero to maximum in accordance with adjustment of the weights.

In the position of the weights 1 and 2 shown in Fig. 5 there is a zero unbalance because a weight 30, preferably of annular form, is permanently xed to the rotating oscillator housing 11. The weight produces an unbalance equal in magnitude to the maximum unbalance produced by weights 1 and 2 and by the weight of the unbalanced portion of screws 3 and 4 when they are in the extreme position shown in Fig. 5. When the weights 1 and 2 are moved to their extreme opposite left hand direction relative to the axis of rotation 26, then the resultant unbalance force is a maximum. In this case, the unbalance of weight 30 and the net unbalance of weights 1 and 2 together with the net unbalance of screws 3 and 4 are all in the same direction so that the oscillator is set at its maximum force. Intermediate positions of the mass 1, 2, 3 and 4 between the two extremes produce intermediate forces on the oscillator.

The addition of weight 30 makes it possible to reduce the capacity of the adjustable eccentric weights 1, 2, 3 and 4 to one-half the capacity of the oscillator. The oscillator can, of course, yoperate without weight 30 but the Weight 30, when used, has a cooperative relationship to the other weights to obtain the advantage mentioned. The weight 1 is preferably telescopically received within fixed weight 30 in the zero balance adjustment.

Thus it is seen that rotation of worm 10 insures opposite rotation of worm gears 8 and 9 so as to cause the left and right hand screws 3 and 4 to move the weights 1 and 2 to any desired position. The helical angle of the teeth in the dorm 10 is designed so as to lock the worm gears 8 and 9 in any position to which they are adjusted. This locking action is suicient to resist the centrifugal force of the weights tending to reversely drive the worm, if the gear ratio between the worm and gears is in excess of a ratio of ten-to-one. A ratio of twenty-to-one has actually been used in one design. Additionally, the pitch of the screws 3 and 4 is also suiiicient to lock the weights in any of their adjusted positions. The self-locking action of the screws may be used alone in case a self-locking action by the adjusting gears 8, 9 and 10 is not desired.

The oscillator is driven, and adjustment of the weights is made, in the manner diagrammatically shown in Fig. 2. To drive the oscillator a pulley is suitably rigidly secured to an extension 36, Fig. 4, of the oscillator housing journalled for rotation. This pulley is driven by a main drive motor 37, Fig. 2, through a pulley 38, belt 39, pulley 40, intermediate shaft 41, suitably journalled in a fixed portion 42 of the frame of the testing machine, pulley 43 and belt 44. These and similar belts and pulleys described herein are so-called timing belts having belt cleats and teeth on the pulley surfaces so that no slippage occurs.

The main drive motor 37 is connected to a pulley 47 through a gear transmission 46, preferably a planetary gear transmission, having a housing 46' journalled for selectable rotation in a stationary portion 46(a) of the testing machine frame. Such a planetary gear transmission is well known and has many forms. Hence it need not be described in detail except to point out that, generally, the input power shaft 48 drives a sun gear while the planet gears are connected to the output shaft 49 of pulley 47. The ring gear of gear transmission 46 is formed integrally with the gear transmission housing so that when the gear transmission housing is prevented from rotating, power is transmitted through shaft 48, pulley 47, belt 50, idler pulleys 51 and 52, belt 53, and pulley 54 to rotate shaft 55 connected to an extended shaft end 56 of the worm 10. So long as shaft S5 rotates at exactly the same speed and in the same direction as the oscillator housing 11 there will be no relative rotation between the worm 10 and worm gears and accordingly the weights 1 and 2 will remain with a fixed degree of eccentrieity relative to axis of rotation 26. In order to have the pulleys 35 and 54 rotate at the same speed and in the same direction the speed change from pulley 38 to pulley 40 must be exactly the same as the combined speed changes through gear transmission 46 and pulleys 47 and 51. However, inasmuch as I propose to rotate the gear transmission housing 46 only when the worm 10 is to be rotated so as to adjust the eccentricity of the weights 1 and 2, I provide the gear transmission with a ratio other than 1.0 between the input and output shafts 48 and 49. Yet it is necessary that the pulleys 51 and 40 have exactly the same speed when the gear transmission housing 46 is held stationary. To accomplish this the gear ratio through the vgear transmission for shafts 48 and 49 is, say, two-tothree and the ratio between pulleys 38 and 40 is also twoto-three or, in other words, identical non-unity ratios in each case. The ratio between pulleys 47 and 51 is one-toone and similarly for the pulleys 52, 54 and 43, 35. By having the ratio of two-to-three the same through the gear transmission as it is between pulleys 38 and 40 insures that pulleys 40 and S1 rotate at exactly the same speed when the gear transmission housing is stationary. When the gear transmission housing 46 is rotated the nonunity gear ratio through the gear transmission causes pulley 47 to rotate relative to input shaft 48 and accordingly cause relative rotation between the worm shaft 55 and the oscillator housing 11 thereby to adjust the eccentricity of the weights.

To effect such rotation of the gear transmission housing 46 there is provided an adjusting motor 60, pulley 60', and belt 60a. A multi-turn potentiometer 61 is connected mechanically to the shaft of the adjusting motor 60 through a speed reducer 62 of proper gear ratio. When the adjusting motor displaces the oscillator masses 1-4 it also displaces the slider arm of potentiometer 61. A remote control console has a potentiometer 63 similar to potentiometer 61 and the two potentiometers are connected into the same electrical circuit and powered by the same supply voltage 64. When the slider arms of these potentiometers are in the same relative position, the voltage between the sliders is zero and a sensitive relay 65 connecting these two sliders is electrically balanced so that its two contacts 65 are open. When the potentiometer 63 is at a higher setting than potentiometer 61, the actual force setting of the mechanical oscillator is less than the required force as set on dial 66, which is mechanically connected to slider arm of potentiometer 63. This closes one of the contacts of sensitive relay 65 which in turn starts the adjusting motor 60 in the proper direction, through one of two electrical contacts 65. This operation continues until the required oscillator setting is reached.

If potentiometer 63 is at a lower setting than potentiometer 61 then the other contact 65 of relay 65 closes and the adjusting motor is operated in the opposite direction so as to reduce the oscillator force setting to the required value as set on dial 66. A revolution counter 67 driven by adjusting motor 60, which is of the brake motor type, indicates independently the setting of the oscillator.

The non-unity speed ratio between the input and output shafts of the differential transmission 46 has reference to such ratio being other than plus l. A negative ratio of one (l) can be used as illustrated in Fig. 6 in which a bevel gear differential 70 is interposed between the input shaft of a driving motor 71 and an output shaft 72. The input shaft has a gear 73 driving a gear 74, intermediate shaft 75, and pulleys 76 and 77 with a belt 78 similar to the corresponding pulleys and belts 43, 35, and 44 of Fig. 2 to perform the same functions thereof. The output shaft 72 is connected through belts and pulleys to drive a pulley 79 corresponding to the pulley 54 of Fig. 2. The normal rotation of pulleys 77 and 79 are in the same direction because of gear 74 being rotated in the same direction as output shaft 72 by reason of the differential gears 80 interposing ya reverse rotation to the output shaft compared to the direction of the motor 71. In order to effect relative angular movement between the pulleys 77 and 79 for adjusting the eccentric position the differential gears 80 are mounted upon a usual spider 81 whose angular position may be adjusted by an adjusting motor 82 corresponding to motor 60 and a suitable belt and pulley connection 83. To avoid the use of a gear transmission the oscillator may be rotatably driven directly by a synchronous motor 85, Fig. 7 and pulleys and belts generally indicated at 86 and 87 corresponding to pulley 3S. A synchronous adjusting motor 88 connected in parallel with motor 8S can be connected directly to the worm shaft 56. As long as these motors run at precisely the same speed the oscillator weight would maintain a fixed setting. To adjust the setting, the motor housing could be provided with a circular gear 90 to be rotated in any suitable manner by a pinion 91. The rotation of the motor casing to any desired extent would provide the necessary differential rotation between the worm shaft S6 and oscillator housing thereby effecting `a desired degree of adjustment of the eccentric weight.

The versatility afforded by the controls hereof is seen from the following several situations. To conduct tests under program loading, it is only necessary to have several potentiometers 63 and dials 66, each being initially set at a different load value as required for the test. Only one of such potentiometers would be connected at any one time to potentiometer 61. When the predetermined number of cycles have been applied relays would operate and disconect one load potentiometer and connect another which automatically readjusts the oscillator force while the machine is in operation. Accelerated fatigue testing can be conducted by simply operating adjusting motor 60 at a predetermined rate or by rotating dial 66 at a predetermined rate. Fatigue testing under constant energy can be accomplished by means of sensing elements to measure the energy in the specimen which in turn operate relays to adjust motor 60 to the required position for the necessary mechanical oscillator force. Vibratory testing under constant acceleration can be accomplished by using an acceleration sensing element on a vibratory table so as to operate relays to adjust the oscillator setting automatically as the speed of operation is changed.

Thus it is seen that my oscillator apparatus has a high degree of ilexibility of operation and control. The oscillator setting may be adjusted Whether the oscillator is rotating or stationary and in either event the oscillator will be self-locking in any eccentric position to which the weights are adjusted. The oscillator, per se, is extremely rugged and because of its particular combination and arrangement of elements it can be used for very large sizes and capacities. The ability to move the weights along a linear path insures that regardless of the position of the weights it is possible to have for each equal increment of adjusting movement of motor 60 a corresponding incremental adjustment of the oscillator force. Such a `linear relationship permits the dial 66 to have equally spaced calibrations representing increments of force change. The functional relation of the fixed weight 30 to the adjustable weights 1 and 2, makes it possible to reduce the capacity of the adjustable eccentric weight to one-half the capacity of the oscillator, this being a very desirable feature in enlarging the range of the usefulness of the oscillator with minimum cost.

It lwill, of course, be understood that various changes in details of construction and arrangement of parts may be made by those skilled in the art without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. An oscillator apparatus comprising, in combination,

a housing, means for supporting said housing for rotation about an axis, driving means to rotate said housing about said axis, a force producing eccentric mass supported by said housing for rotation therewith, means for linearly moving said mass in a direction substantially at right angles to said axis to adjust the eccentricity of the mass and thereby vary the force produced thereby during rotation of the housing, said linearly moving means including a pair of parallel screws, nuts for said screws supported in said housing, and means cooperative with said driving means for effecting relative rotation between the screws and nuts to linearly adjust said mass during said rotation of said housing and mass.

2. An oscillator apparatus comprising, in combination, a housing, means for supporting said housing for rotation about an axis, driving means to rotate said housing about said axis, a force producing eccentric mass supported by said housing, means for linearly moving said mass in a direction substantially at right angles to said axis to adjust the eccentricity of the mass and thereby vary the force produced thereby during rotation of the housing, said linearly moving means including a pairof parallel screws, nuts for said screws rotatably supported in said housing and each nut being secured inside a gear, another gear commonly engaging said two gears so as to rotate both nuts simultaneously to effect axial movement of the screws and linear adjustment of the eccentric mass, and means selectively cooperative with said driving means to rotate said other gear with respect to said first two gears while said driving means is rotating said housing and said mass.

3. An oscillator comprising, in combination, a housing, means for supporting said housing for rotation about an axis, driving means to rotate said housing about said axis, a force producing mass supported by said housing,

a pair of parallel right and left hand threaded screws rigidly connected to said mass, a pair of nuts for said screws journalled in said housing so as to support said mass for movement in a linear direction at substantially right angles to said axis, worm gears secured to said nuts in generally tangential relation to each other, a worm journalled in said housing to commonly engage said worm gears at their generally tangential points so as torotate the worm gears in opposite directions and thereby adjust the linear position of the mass to a desired degree of eccentricity with respect to said axis thereby to produce a corresponding force during rotation of the housing and mass, and selectively controllable means cooperative with said driving means .to rotate said worm with respect to said worm gears during said rotating of said housing and mass.

4, An oscillator apparatus comprising, in combination, a housing, means for supporting said housing for rotation about an axis, driving means to rotate said housing about said axis, a pair of weights disposed on opposite sides of said axis and rigidly connected together, means for supporting said weights by said housing, and means for moving said weights linearly in a direction substantially at right angles to said axis so as to establish a dcsired eccentric position of the weights and thereby produce a desired force upon rotation of the housing and weights, and selectively controllable rotary means cooperative with said driving means to actuate said moving means during said rotation of said housing and said weights.-

5. The combination set forth in claim 4 further characterized by the provision of means independent of said weight-moving means for neutralizing the force producing effect of said weights when they are in a predetermined linear position.

6. The combination set forth in claim 4 further characterized by the provision of a third weight rotatable with the housing and positioned with respect to said pair of weights so as to neutralize the force producing effect thereof when the pair of weights are in a predetermined linear position.

7. The combination set forth in claim 4 further characterized by the provision of a third weight formed as a part of the housing for rotation therewith, such weight having a mass and position with respect to said pair of weights so as to neutralize the force producing effect of said pair of weights when they are in a predetermined linear position.

8. The combination set forth in claim 4 further characterized by the provision of third weight means formed as part of said housing for rotation therewith, said third weight means having such mass and positional relationship with said pair of weights as to neutralize the forceproducing effect of said pair of weights when the latter are in one linear radial position and to add to said forceproducing effect when said pair of weights are in another linear radial position.

9. An oscillator apparatus comprising, in combination, a housing, means for supporting said housing for rotation about an axis, driving means to rotate said housing about said axis, a pair of parallel screws disposed on opposite sides of said axis and extending through said housing in a direction at substantially right angles to such axis, a pair of weights one of which is secured to one end of said screws on one side of said housing and the other of which is secured to the other end of the screws on the other side of the housing, means cooperative with said driving means during said driving rotation for moving said screws linearly through said housing to any desired position whereby in one extreme position one weight is -adjacent to the housing and the other weight is remote therefrom thereby to produce a maximum force during said rotation of the weights and housing, and a lesser force is produced for corresponding intermediate linear positions of said screws relative to the housing.

10. An oscillator apparatus comprising, in combination, a mass, means for rotatably and eccentrically supporting said mass about an axis of rotation to produce a vibratory force, mechanism for adjusting the eccentric position thereof so as to vary the force produced by the rotation of the mass, said mechanism being rotatable with the mass and at the same speed thereof when the mass has a set eccentric position and being movable relative to the mass when the eccentricity thereof is being adjusted, a motor, a transmission driven by said motor and having two shafts rotated in a non-unity speed ratio relative to each other, means for rotatably driving said mass from one of said shafts, means for rotatably driving the adjusting mechanism from the other of said shafts at the same speed as the rotation of the mass when the mass has said set eccentric position, and means for changing the relative angular relationship between said transmission shafts so as to effect relative movement between the mass and the adjusting means therefor thereby to adjust the eccentric position of the mass.

11. The combination set forth in claim l further characterized by the provision of a lever upon which is supported the mass and the means for rotatably supporting the same together with the mechanism for adjusting the eccentric position of the mass; means for pivotally supporting said lever at a point located away from the axis of rotation of the mass thereby to cause the vibratory force of the mass to oscillate the lever; and the means for rotatably driving said mass from one of the shafts includes an intermediate rotary element whose axis of rotation is co-axial with the oscillatory axis of said lever, and a driving connection between said intermediate rotary element and said mass, whereby such driving connection is maintained constant during oscillation of the mass and lever.

12. The combination set forth in claim 1l further characterized by the provision of a lever upon which is supported the mass and the means for supporting the same together with the mechanism for adjusting the eccentric position of the mass; means for pivotally supporting said lever at a point located away from the axis of rotation of the mass thereby to cause the vibratory force of the mass to oscillate the lever; and the means for rotatably driving the adjusting mechanism from one of the shafts includes an intermediate rotary element whose axis is co-axial with the pivotal axis of said lever, and a driving connection between said intermediate rotary element and said mass, whereby such driving connection is maintained constant during oscillation of the mass and lever.

13. The combination set forth in claim 12 further characterized by the provision of a lever upon which is supported the mass and the means for rotatably supporting the same together with the mechanism for adjusting the eccentric position of the mass; means for pivotally supporting said lever at a point located away from the axis of rotation of the mass thereby to cause the vibratory force of the mass to oscillate the lever; and the means for rotatably driving said mass from one of the shafts and for rotatably driving the adjusting means from the other of said shafts includes intermediate coaxial rotary elements whose axis of rotation is co-axial with the pivotal axis of said lever, and driving connections respectively between one of said intermediate rotary elements and said mass and between the other element and said adjusting mechanism, whereby the driving connections are both maintained constant.. during oscillation of the mass and lever.

14. In oscillator apparatus, in combination, a mass, means for rotatably and eccentrically supporting said mass about an axis of rotation, a rotary shaft concentric with said axis, means operationally connecting said shaft and said mass and operative by rotational angular displacement between said mass and said shaft to change the eccentricity of said mass, first driving means to rotate said mass at a pre-determined speed, second driving means adapted to normally rotate said shaft synchronously with said mass, adjusting means electrically operable during said driving rotation to establish a rotative speed differential between said two driving means for effecting said rotational angular displacement and said resulting change in said eccentricity of said mass, electrical means including a remote control station for selectively controlling said adjusting means, and means at said remote control station for pre-selecting the extent of said adjusting change in said eccentricity of said mass.

15. Oscillator apparatus according to claim 14 wherein said first and second driving means include respectively a iirst and a second synchronous electric motor connected to current supplies of identical frequency, and wherein said adjusting means includes means to rotate the normal stator of said second synchronous motor.

References Cited in the tile of this patent UNITED STATES PATENTS 2,483,318 Lazan Sept. 27, 1949 2,505,753 Cleveland May 2, 1950 2,542,227 Bernhard Feb. 20, 1951 2,852,162 Nauta Sept. 16, 1958 2,930,244 Hutchinson et al. Mar. 29, 1960 

